Magnetic shear locks which are gaining more popularity comprise an electromagnet which is mounted into a cutout in the soffet of a doorway and an armature which is mounted within the top of the door and adapted to be attracted by the electromagnet, when energized, to secure the door in the frame. The doors may be hollow which have reinforcing ribs or rails extending horizontally below the top edge of the door. These rails may vary in depth from the top edge of the door dependent upon the manufacturer of the door. Additionally if the top rail is not parallel with the top of the door may be difficult to mount the armature parallel with the electromagnet. A further consideration in mounting the armature is where the door is not hung completely square so that the top edge is parallel with the soffet. Examples of electromagnetic shear locks are set forth in U.S. Pat. Nos. 4,487,439 and 4,562,665. Electromagnetic shear locks, while providing a magnetic holding force must also rely on a mechanical retaining force to ensure security. For this additional reason it is imperative that the electromagnet and armature be properly aligned.
Accordingly, the present invention provides a new and improved mounting mechanism for the armature of an electromagnetic shear lock on inverted top rail doors.